Guidelines for reducing acrylamide in processed

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Indian Food Industry Mag Vol 36 No 1, Jan-Feb 2017

Guidelines for reducing acrylamide in processed potato products Vijay Paul* R Ezekiel1 and Rakesh Pandey2 *ICAR-Central Potato Research Institute-Campus (CPRI-Campus), Modipuram, Meerut, UP - 250 110, India; Present: Division of Plant Physiology, ICAR-Indian Agricultural Research Institute (IARI), New Delhi -110 012, India. Crop Physiology and Post-Harvest Technology, ICAR-Central Potato Research Institute (CPRI), Shimla, Himachal Pradesh - 171 001, India

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Division of Plant Physiology, Indian Agricultural Research Institute (IARI), New Delhi - 110 012, India. *E-mail: [email protected] potato in India, about 68% is utilized for table purpose, 7.5% for processing, 8.5% as seed for next year planting and remaining 16% represents postharvest losses.

Summary In the recent past, India has made substantial progress not only in production and productivity of potatoes but also in utilizing potatoes for processed products mainly chips and French fries. This quantitative improvement now demands for enhancement of qualitative aspects of processed potato products. Among the various issues that are associated with quality aspects, one of the important issues is the levels of acrylamide in different processed potato products. This article brings about various aspects which are directly or indirectly linked with the levels of acrylamide in processed potato products. Besides covering the concerns and various health issues related to acrylamide in our diet, the article suggests guidelines that can assist in achieving an overall reduction in the levels of acrylamide in processed potato products. Both, organized as well as unorganized sectors involved in the potato processing will be benefited from the guidelines presented here. These guidelines along with the outcome from the suggested lines of future research work will be of help in further improving the qualitative aspects. All these efforts will allow India to compete globally in terms of quality and safety aspects of different processed potato products. The information presented here will be of relevance and practical use not only to processors and potato based processing industries but also to potato growers, cold store owners and consumers as well.

About 25 years back, suitable raw material for chips and French fries was not available in India. However, progress in the past, especially in the last one decade, has enabled India in channelizing the potatoes into processing sector. Today, potato processing industry in India is supported by round the year availability of quality raw material. At present, 3.42 million metric tonnes of potatoes are processed and this is about 7.5% of the total potato production in India. Comparatively, this percentage is quite low as the Netherlands process about 75% of the potato production (40% into food products and 30 % for making potato starch) and in UAS this figure is up to 40 to 50%. In addition to the main processed products like chips, French fries and Alu Bhujia, other processed products in India are flakes, laccha and dehydrated chips. Today, market of processed potato products in India is growing at the rate of 15-20% annually with chips and French fries as the major processed products. In the next 30 to 35 years, demand for processing grade quality potatoes in India is expected to rise at the fastest pace for French fries (11.6% annual compound growth rate (ACGR) followed by potato flakes/ powder (7.6%) and potato chips (4.5%). Demand for processing grade potatoes will increase to 25 million tonnes by the year 2050, at an ACGR of about 5.61%. At this juncture, it is very important that our attention should now be focused on the qualitative aspects of processed potato products. Importance of this aspect can be understood in view of growing awareness of general public on health, safety and environmental issues. In addition to the demand for quantity, today people are also concerned with quality and safety aspects as well. There are number of quality related issues that are linked with the final quality and safety of the processed potato products. These include timely availability of suitable processing grade variety, its growing and storage conditions, residue limits of CIPC [isopropyl N-(3-

Key words: Acrylamide, Carcinogenicity, Chips, French fries, Neurotoxicity, Potato processing, Potato storage, Reducing sugars, Safety issues

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Introduction With an average productivity of 22.09 metric tonnes per hectare, India produced 45.57 million metric tonnes of potatoes from 2.06 million hectares of area in 2016 and ranked second in the world. India contributes about 12% of the global potato production of 379.75 million metric tonnes. Out of total annual production of 36

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and aspartic acid) with ammonia results into the formation of low amounts of acrylamide by thermal decomposition. Levels of acrylamide as reported in chips and French fries made from potato are presented in Table 1. Among different categories of processed food products, highest levels of acrylamide have been reported in French fries, potato chips and in other fried, deep-fat fried or ovencooked potato products.

chlorophenyl) carbamate, a sprout suppressant used during storage of potatoes], concentration of reducing sugars in potatoes, browning of fried products and levels of acrylamide in processed potato products. This article is written with an objective to highlight different aspects that determine levels of acrylamide in processed potato products. Various health and safety issues associated with acrylamide and its metabolite (breakdown product) glycidamide are presented here. In later part of this article, different guidelines that can assist in achieving an overall reduction in the levels of acrylamide in processed potato products are suggested. Lastly, future lines of work are suggested. The article will be useful in further improving the quality of processed potato products in India. The information presented here will be of interest and use to potato growers, cold store owners, processors, potato processing industries and the consumers.

Concerns, Health and Safety issues associated with Acrylamide and Glycidamide (major metabolite/breakdown product of acrylamide) The classification of acrylamide as a potential carcinogen (Group 2A) and its listing as Category 2 of mutagens has raised lots of concerns. These concerns were further highlighted and confirmed by many workers and agencies. Till date, acrylamide has been found to be associated with the cancer/tumors of ovary, breast, bladder, prostate, gastrointestinal tract, lung, brain, nervous system, oral cavity, peritoneum, thyroid gland, mammary gland, uterus and clitoris. Besides being carcinogenic, acrylamide is a reproductive and developmental toxin with mutagenic properties for mammalian system.

Acrylamide in Processed Potato Products Acrylamide (C3H5NO) is an odourless crystalline solid, which is highly soluble in water (2004 g per litre of water at 25oC) and organic solvents. It is a byproduct which is formed when certain carbohydrate-rich foods are fried, baked or roasted at temperatures higher than 120 °C. Chemical reaction which is basically responsible for the formation of acrylamide in starchy foods is Maillard reaction (Fig. 1). This reaction involves condensation of amino acid (primarily asparagine) with reducing sugars (fructose or glucose) at temperatures above 120 oC on frying or heating. It is this Maillard reaction which is mainly responsible for browning of processed food products. The overall browning that occur during frying of food products has two components i.e., acrylamidedependent and acrylamide-independent browning. Besides the Maillard reaction, decarboxylated asparagine (3aminopropionamide), when heated, can also generate acrylamide in the absence of reducing sugars. In addition to this, degradation of amino acids (glutamine, cysteine

Glycidamide is a major metabolite of acrylamide. When acrylamide is consumed through food, the body converts it to glycidamide. This metabolite is generated by cytochrome P4502E1 (CYP2E1). Glycidamide is a clastogenic agent which forms DNA adducts and thereby glycidamide is responsible for genotoxic action. In fact, as per the current understanding, it is the glycidamide which is responsible for carcinogenic property/action of acrylamide while, the acrylamide (as such) accounts for neurotoxicity in humans and animals. Acrylamide has a direct inhibitory effect on presynaptic function and it also reduces neurotransmission at central and peripheral synapses by disturbing signaling pathways. In addition to carcinogenic and neurotoxin, acrylamide, being a type-2 alkene, can interact with endogenous unsaturated

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100 g-1 FW). At storage temperature of 14 oC, levels of acrylamide in non-irradiated potatoes of Kufri Chipsona-2 changed from 416.4 (initial value) to 451.8 (after 2 months), 511.9 (after 4 months) and 548.8 (after 6 months). Similar values for irradiated potatoes were 416.4 (initial value), 432.7 (after 2 months), 469.3 (after 4 months) and

aldehydes and thereby accelerate the onset and development of atherosclerosis, diabetes, Alzheimer’s diseases and other pathogenic conditions that have cellular oxidative stress as a molecular etiology.

Acceptable Limits of Acrylamide

502.6 (after 6 months).

As per European Commission (EC) 2011, indicative (recommended) levels of acrylamide in chips and French fries are 1000 and 600 μg kg-1, respectively.

Acrylamide in French fries prepared from freshly harvested potato tubers of different varieties also showed minimum concentration in processing grade varieties namely Kufri Chipsona-1, Kufri Chipson-2, Kufri Chipsona-3, Kufri Himsona, Kufri Frysona and Kufri Chandramukhi (ranging from 63 to 101 μg kg-1) But, the varieties which are generally considered unsuitable for processing such as Kufri Arun, Kufri Anand, Kufri Giriraj, Kufri Ashoka etc. had significantly higher concentrations of acrylamide (364 to 3,686 μg kg-1). List of most popular varieties of potato grown in India is presented in Table 2. In addition to these Indian varieties, some of the exotic varieties which are grown in India for processing purpose are Lady Rosetta and Atlantic (for chips) and Shepody, Kennebec and Santana (for French fries).

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Levels of Acrylamide in Indian Processed Potato Products Acrylamide content in potato chips prepared from freshly harvested tubers of Indian potato varieties vary widely. Minimum concentrations of acrylamide were found in processing varieties Kufri Chipsona-2 (40 μg kg1 of chips) and Kufri Chipsona-1 (109 μg kg-1). Other varieties such as Kufri Jyoti, Kufri Lauvkar and Kufri Chandramukhi, which are also suitable and used for processing at commercial scale, had concentrations of acrylamide ranging from 108 to 306 μg kg-1. On the other hand, varieties which are considered unsuitable for processing and more suitable for table purpose such as Kufri Anand, Kufri Girdhari, Kufri Sutlej, Kufri Lalima and Kufri Pukhraj etc. have very high concentrations of acrylamide (more than 1000 μg kg-1). In a study, contents of reducing sugars, asparagine and acrylamide were determined in chips made up of eight Indian potato varieties namely Kufri Chipsona-2, Kufri Anand, Kufri Sutlej, Kufri Bahar, Kufri Surya, Kufri Lauvkar, Kufri Jyoti and Kufri Badshah. Levels of all these constituents were influenced to a significant level by storage temperature (4 and 14 oC), duration of storage (2, 4 and 6 months) and the sprout suppressant treatment (irradiating the stored potato tubers). Variety Kufri Chipsona-2 showed lowest levels of reducing sugars (68.07 mg 100 g-1 FW) and acrylamide (416.75 g kg-1 of chips). Variety Kufri Lauvkar showed lowest levels of asparagine content (207.44 mg

Guidelines for Reducing Acrylamide in Processed Potato Products

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Select suitable processing grade variety as per the requirement and region of cultivation. The processing varieties should possess high dry matter (> 20 %) and low reducing sugars (< 0.10 %).

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There is a positive correlation of acrylamide content with the level of reducing sugars and also with the colour score of fried products. The level of acrylamide can be reduced by lowering the concentration of reducing sugars in potatoes. As per international limits, levels of reducing sugars should be less than 100 and 150 mg per 100 g FW of potato for chips and French fries, respectively.

Indian Food Industry Mag Vol 36 No 1, Jan-Feb 2017

Levels of sugars in potatoes are influenced more by variety, growing conditions and storage conditions (especially the temperature) than any other factor. So, besides the proper selection of variety, temperature that prevails during growth and storage of potatoes play major role in determining the levels of reducing sugars present in potatoes. Storage of potatoes in cold stores maintained at 10 to 12 ºC (with 85-90 % RH) is widely accepted as the optimum storage temperature for maintaining lower or acceptable levels of reducing sugars in potatoes. Therefore, processing grade potatoes stored at above said temperature should be used when freshly harvested potatoes are not available.

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Largest increase in acrylamide levels usually occur when the potatoes are used after 6 months of storage at 10 to 12 ºC. While, the increase in acrylamide content in processed products obtained from potatoes stored up to 6 months is usually small. It is, therefore, recommended that the potatoes meant for processing should fall within the optimal storage duration ranging from 2 to 6 months and not beyond this.

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In addition to large-scale storage of potatoes in cold stores maintained at 10 to 12 ºC, different types of non-refrigerated traditional/on-farm storage methods (heaps, pits, a dark room as such or with provision of evaporative passive cooling, spreading tubers on floor, storing in bins, ventilated wooden or bamboo structures and hanging potatoes in bamboo baskets) are also used and preferred by farmers for short-term (2 to 4 months) storage of potatoes in India. These traditional methods are not only highly cost-effective but they have also proved to be helpful in extending the time period for marketing of potatoes. Since higher temperature prevails during the period of storage (ranging from 21 to 32 ºC with RH 51 to 95 %), these methods help in maintaining low levels of reducing sugars in stored potatoes. This in-turn retains the suitability of potatoes for processing as well as table purposes. Over a period of time, improvements in these onfarm storage methods based on scientific findings and synchronization of storage time with the schedule of potato crop production have made these methods more acceptable and popular among the farmers, especially for those who belong to low or medium income groups. Today, thousands of metric tonnes of potatoes are being stored by these on-farm methods in states like Punjab, Uttar Pradesh, Madhya Pradesh, Gujarat, Maharashtra and Karnataka. These methods have proved their potential and usefulness in supplying quality potatoes to processing industry for 2 to 3 months after the harvest of potato crop. 39

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Browning of processed potato products is of two types. First is non-enzymatic browning and it is mainly mediated by Millard reaction and it contributes for the formation of acrylamide. Second type of browning is referred as enzymatic browning. Here, discolouration takes place due to oxidation of phenolic compounds by the enzyme polyphenol oxidase. Quinones are formed as a result of this enzymatic reaction and they impart brownish colour on the product. This type of browning, however does not contribute towards the formation of acrylamide. Blanching step (dipping of cut slices into hot water at temperature of 60-80 °C for 2-3 minutes) is essentially followed during the processing. This simple step takes care of enzymatic browning. It is therefore that the browning that still occurs, in spite of blanching step, is mainly due to non-enzymatic reaction (Millard reaction) and it will contribute for acrylamide formation in the processed potato products. But, at the same time, it is also true that this blanching step not only controls enzymatic browning but it also brings about removal (washout) of some reducing sugars and asparagine as well and in this way the blanching step also contributes in reducing the acrylamide formation.

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There exists a significant positive correlation between acrylamide content and chip colour score. Chips/French fries which are the brownest are also found to be the highest in acrylamide content and those which are relatively white/pale/yellowish are low in their acrylamide content. It is therefore, one of the straight-forward ways to improve the overall quality and to reduce the levels of acrylamide is to avoid visual browning while frying or baking. This is also a recommendation by WHO (World Health Organization).

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Frying temperature and frying time have drastic influence on the extent of acrylamide formation. Acrylamide formation is significantly enhanced towards the end of the frying process. Frying temperatures above 175°C (especially during the end) has been shown to cause sharp rise in the levels of acrylamide. So, it is suggested that initial frying temperature should not exceed 170°C. Further reduction in the formation of acrylamide can be achieved by lowering the temperature to 150°C towards the end of the frying period. To enable better control over frying temperatures, it is necessary to improve the reliability and accuracy of temperature controlling system of frying equipments.

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On the basis of colour, oil content and acrylamide level the best French fries were obtained after 5 minutes of frying at 180 oC. Overcooking of French fries should be avoided. This is because of the fact that overcooked French fries show a very high level

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Indian Food Industry Mag Vol 36 No 1, Jan-Feb 2017

of acrylamide (up to 10,000 zg kg-1or even more). o

approach. IUFoST 2006 DOI: 10.1051/ IUFoST:20060719. http://iufost.edpsciences.org; http://dx.doi.org/10.1051/IUFoST:20060719 EC (2011). European Commission Recommendation of 10 January 2011 on investigations into the levels of acrylamide in food. http:// www.ec.europa.eu/ food/food/chemicalsafety/contaminants/ recommendation_10012011_acrylamide_food_en.pdf EFSA (2015). Acrylamide. http://www.efsa.europa.eu/en/ topics/topic/acrylamide. Elmore S, Briddon A, Dodson A, Muttucumaru N, Halford N, Mottram D (2015). Acrylamide in potato crisps prepared from 20 UK-grown varieties: effects of variety and tuber storage time. Food Chem. 182:1-8 Ezekiel R, Singh B, Kumar D, Paul V, Das M (2005). Storage of potatoes at 10-12 oC with CIPC treatment in commercial cold stores. Potato J. 32:211-212. Ezekiel R, Mehta A, Singh B, Kumar D, Kumar NR, Paul V, Das M (2005). CIPC [Isopropyl N-(3chlorophenyl) carbamate] for sprout suppression in potatoes during storage. Technical Bulletin No. 69, Central Potato Research Institute (CPRI), Shimla. FAOSTAT (2015). http://faostat3.fao.org/download/Q/ QC/E Food Drink Europe (2013). Food drink Europe acrylamide toolbox. http://ec.europa.eu/food/food/ chemicalsafety/contaminants/ toolbox_acrylamide_201401_en.pdf Gokmen V, Akbudak B, Serpen A, Acar J, Turan ZM, Eris A (2007). Effects of controlled atmosphere storage and low-dose irradiation on potato tuber components affecting acrylamide and color formations upon frying. Eur. Food Res. Technol. 224:681-687. Gokmen V, Palazoglu TK, Senyuva HZ (2006). Relation between the acrylamide formation and time– temperature history of surface and core regions of French fries. J. Food Eng. 77:972-976. Granda C, Moreira RG (2005). Kinetics of acrylamide formation during traditional and vacuum frying of potato chips. J. Food Process Eng. 28:478-493. Halford NG, Muttucumaru N, Powers SJ, Gillatt PN, Hartley L, Elmore JS, Mottram DS (2012). Concentrations of free amino acids and sugars in nine potato varieties: effects of storage and relationship with acrylamide formation. J. Agric. Food Chem. 60:12044-12055. Kumar D, Paul V, Ezekiel R (2005). Chipping quality of potatoes stored in heap and pits in sub-tropical plains of India. Hort. Sci. (Prague) 32:23-30.

New frying method such as vacuum frying reduces the acrylamide formation. Further, treatment of potato slices with non-transition state cations such as Ca 2+ has also been found to reduce the acrylamide formation in foods during heating.

Conclusions and Future Perspectives Development and availability of suitable processing grade varieties and their adaptability to different regions of country along with simultaneous improvements and spread of short-term and long-term storage methods has resulted in better supply system and round the year availability of processing-grade potatoes. All these developments have helped in establishing a stable base for processing industries in India. In addition to organized sector, high proportion of potato in India is also processed by unorganized sector. Information presented in this article are of relevance and use to potato processing sector in general and to unorganized sector in particular. The information and guidelines presented here will be helpful in reducing the percentage of browning and acrylamide formation in processed potato products. This will add to an overall improvement in the quality and contribution of potato in the overall progress of processing sector in India. Some of the future lines of research work that can assist in achieving still higher targets of qualitative improvements are as follows. Varietal development with additional traits like resistance to cold-induced sweetening (even under prolonged storage period of 6 to 9 months at 2-4 oC), extended duration of dormancy period (from present duration of two months to about four months or even more) and lower levels of reducing sugars (ranging from 20 to 60 mg per 100 g fresh weigh of tuber) at the time of harvest and even after short- or long-term storage). With these priorities and concerted efforts in the direction of developing varieties with above traits and wider adaptability to different environments/regions of the country will make us self-sufficient in meeting our present and future demands for wide range of potato-based processed products.

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Further Readings CPRI (2013). Vision - 2050. Central Potato Research Institute (CPRI), Shimla, India. CPRI Annual Report (2009-10). Central Potato Research Institute (CPRI), Shimla, India, pp 21, 35, 4142,118-119. CPRI Annual Report (2011-12). Central Potato Research Institute (CPRI), Shimla, India, pp 13, 112-113. Cummins E, Butler F, Brunton N, Gormley R (2006) Factors affecting acrylamide formation in processed potato products - A simulation 40

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LoPachin RM, Gavin T (2012). Molecular mechanism of acrylamide neurotoxicity: Lessons learned from organic chemistry. Environ. Health Perspect. 120:1650-1957. Mehta A, Ezekiel R (2010). Non-refrigerated storage of potatoes. Potato J. 37:87-99. Mills C, Mottram DS, Wedzicha BL (2009). Acrylamide. In: Stadler RH, Lineback DR Eds. Process-induced Food Toxicants. John Wiley & Sons, Inc. Hoboken, NJ. pp 23-50. Mulla MZ, Bharadwaj VR, Annapure US, Variyar PS, Sharma A, Singhal RS (2011). Acrylamide content in fried chips prepared from irradiated and nonirradiated stored potatoes. Food Chem. 127:16681672. NTP (2013). National Toxicology Program (USA) – Acrylamide. https://www.niehs.nih.gov/health/ assets/docs_a_e/acrylamide_fact_sheet_508.pdf Paul V, Ezekiel R, Singh J, Shekhawat GS (2002). Evaluation of on-farm storage methods of potato in Indo-Gangetic plains. In: Paul Khurana SM, Shekhawat GS, Pandey SK, Singh BP Eds. Potato, Global Research and Development (Vol. II) Proceeding of Global Conference on Potato. December 6-11, 1999, New Delhi. Malhotra Publishing House, New Delhi. pp 1080-1085. Paul V, Ezekiel R (2004). Evaluation of heap and pit methods of potato storage in the central IndoGangetic Plains. Indian J. Agric. Sci. 74:665-668. Paul V, Ezekiel R (2005). Changes in temperature and relative humidity in heap and pit during storage of potatoes. Potato J. 32:205-206. Paul V, Kumar D, Ezekiel R (2005). Effect of crop maturity and on-farm storage on sugar content of potato (Solanum tuberosum L.) tubers. Indian J. Plant Physiol. 3:287-291. Paul V, Ezekiel R (2007). Changes in sugar levels and membrane permeability during storage in potato (Solanum tuberosum L.) tubers previously stored in cold store. Indian J. Agric. Sci. 77:32-35. Paul V, Ezekiel R (2013). Scientific storage options crucial for potatoes. Agric Today (Year Book), The National Agriculture Magazine, pp 134-137. Paul V, Ezekiel, R, Pandey R (2016). Cold storage in India: Present scenario and future directions. Processed Food Industry 19: 25-28. Pau V, Ezekiel R, Kuma D, Pandey R (2016). Availability of processing grade potatoes in India. Processed Food Industry 20:13-18.

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Paul V, Ezekiel, R, Pandey, R (2016). Sprout suppression on potato: Need to look beyond CIPC for more effective and safer alternatives. J. Food Sci. Technol. 53:1-18. Paul V, Ezekiel R, Pandey R (2016). CIPC as a potato sprout suppressant during storage: Present scenario and future perspectives. Processed Food Industry 19: 15-18, 48. Pedreschi F, Mariotti MS, Granby K (2014). Current issues in dietary acrylamide: formation, mitigation and risk assessment. J. Sci. Food Agric. 94:9-20. Pelucchi C, La Vecchia C, Bosetti C, Boyle P, Boffetta P (2011). Exposure to acrylamide and human cancer: a review and meta-analysis of epidemiologic studies. Ann. Oncol. 22:14871499. Shamla L, Nisha P (2014). Acrylamide in deep-fried snacks of India. Food Addit. Contam. 7:220-225. Singh BP (2013). Final report of NAIP sub-project “Value Chain on Potato and Potato Products” CPRI-Campus, Modipuram, UP, India. Stefano VD, Avellone G (2014). Food contaminants. J Food Studies 3:88-103. Virendra Pandit (2015a). McDonald’s potato supplier to double crop area in Gujarat. Business Line 24 September, 2015. http:// www.thehindubusinessline.com/economy/agribusiness/mcdonalds-potato-supplier-to-doublecrop-area-in-gujarat/article3931837.ece Virendra Pandit (2015b). In Gujarat, the red potato is no humble spud. BusinessLine 13 March, 2015. http://www.thehindubusinessline.com/economy/ agri-business/in-gujarat-the-red-potato-is-nohumble-spud/article4504956.ece Vivan Fernandes (2015). Gujarat contract farmers smile as potato price crash. Financial Express 17 February, 2015. http:// www.smartindianagriculture.in/gujarat-contractfarmers-insulated-from-potato-price-crash/ WHO (2002). FAO/WHO consultation on the health implications of acrylamide in food. Summary report of a meeting held in Geneva, 25-27 June 2002. Available at http://www.who.int/foodsafety/ publications/chem/en/acrylamide_full.pdf Xu Y, Cui B, Ran R (2014). Risk assessment, formation, and mitigation of dietary acrylamide: current status and future prospects. Food Chem. Toxicol. 69:112. Zhang H, Zhang H, Cheng L, Wang L, Qian H (2015). Influence of deep-frying using commercial oils on acrylamide formation in French fries. Food Addit. Contam. Part A 32:1083-108